Current tall buildings have many elevator hoistways, but each hoistway only has one cab operating in that hoistway with one counterweight cable attached to the top center of the cab. Therefore, only one cab services each floor throughout the entire hoistway, and the general public normally has access to every cab and every floor in the entire building. This situation leads to inefficiencies for building owners, developers, and operators who would like to construct many fewer elevator hoistways and operate many more elevator cabs in different vertical sections of each hoistway. As land increases in value in desirable urban locations, the financial pressure to construct taller and taller buildings will also increase. Already over 15 buildings worldwide have been constructed, each with more than 100 floors, and at least one of these buildings exceeds 150 floors. Ten more buildings over 100 floors are already under construction, and twelve more are currently planned. If the number of elevator hoistways and their associated lobbies in these and other very tall buildings can be minimized, and the number of elevator cabs that operate in such elevator hoistways can be maximized, then the value, efficiencies, desirabilities and viability of these very expensive tall buildings can also be maximized.
The current situation also leads to inefficiencies and dissatisfactions for companies or individuals that lease or own many adjoining floors in a tall building. Many of them would like their employees, occupants and guests to be able to access all of their adjoining floors without having to take a public elevator between such floors. Most modern companies who lease or own multiple adjoining floors in a tall building would like to have one or more private elevators for all of its employees and guests to use, for reasons of privacy, security, efficiency, and commonality. The same is true for tall residential buildings, where one individual or family leases or owns several adjoining floors. Many employees currently waste a lot of time, effort and their company's money by having to leave the company's premises, go out into a public lobby, wait for a crowded public elevator cab moving the entire length of a long hoistway, and then having to re-enter the company's premises on another floor, not to mention the return trip to the employees desk on the original floor. Company's secrets can also be compromised or lost during this process. But until now private elevators for each of such companies, individuals or residences have been either impossible to construct, too impractical, too inflexible, or extremely costly.